/* -----------------------------------------------------------------------------

  Copyright (c) 2006 Simon Brown                          si@sjbrown.co.uk

  Permission is hereby granted, free of charge, to any person obtaining
  a copy of this software and associated documentation files (the
  "Software"), to  deal in the Software without restriction, including
  without limitation the rights to use, copy, modify, merge, publish,
  distribute, sublicense, and/or sell copies of the Software, and to
  permit persons to whom the Software is furnished to do so, subject to
  the following conditions:

  The above copyright notice and this permission notice shall be included
  in all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
  CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

   -------------------------------------------------------------------------- */

#ifndef SQUISH_H
#define SQUISH_H

//! All squish API functions live in this namespace.
namespace squish {

// -----------------------------------------------------------------------------

//! Typedef a quantity that is a single unsigned byte.
typedef unsigned char u8;

// -----------------------------------------------------------------------------

enum
{
  //! Use DXT1 compression.
  kDxt1 = ( 1 << 0 ),

  //! Use DXT3 compression.
  kDxt3 = ( 1 << 1 ),

  //! Use DXT5 compression.
  kDxt5 = ( 1 << 2 ),

  //! Use a very slow but very high quality colour compressor.
  kColourIterativeClusterFit = ( 1 << 8 ),

  //! Use a slow but high quality colour compressor (the default).
  kColourClusterFit = ( 1 << 3 ),

  //! Use a fast but low quality colour compressor.
  kColourRangeFit  = ( 1 << 4 ),

  //! Weight the colour by alpha during cluster fit (disabled by default).
  kWeightColourByAlpha = ( 1 << 7 )
};

// -----------------------------------------------------------------------------

/*! @brief Compresses a 4x4 block of pixels.

  @param rgba     The rgba values of the 16 source pixels.
  @param mask     The valid pixel mask.
  @param block    Storage for the compressed DXT block.
  @param flags    Compression flags.
  @param metric   An optional perceptual metric.

  The source pixels should be presented as a contiguous array of 16 rgba
  values, with each component as 1 byte each. In memory this should be:

    { r1, g1, b1, a1, .... , r16, g16, b16, a16 }

  The mask parameter enables only certain pixels within the block. The lowest
  bit enables the first pixel and so on up to the 16th bit. Bits beyond the
  16th bit are ignored. Pixels that are not enabled are allowed to take
  arbitrary colours in the output block. An example of how this can be used
  is in the CompressImage function to disable pixels outside the bounds of
  the image when the width or height is not divisible by 4.

  The flags parameter should specify either kDxt1, kDxt3 or kDxt5 compression,
  however, DXT1 will be used by default if none is specified. When using DXT1
  compression, 8 bytes of storage are required for the compressed DXT block.
  DXT3 and DXT5 compression require 16 bytes of storage per block.

  The flags parameter can also specify a preferred colour compressor to use
  when fitting the RGB components of the data. Possible colour compressors
  are: kColourClusterFit (the default), kColourRangeFit (very fast, low
  quality) or kColourIterativeClusterFit (slowest, best quality).

  When using kColourClusterFit or kColourIterativeClusterFit, an additional
  flag can be specified to weight the importance of each pixel by its alpha
  value. For images that are rendered using alpha blending, this can
  significantly increase the perceived quality.

  The metric parameter can be used to weight the relative importance of each
  colour channel, or pass NULL to use the default uniform weight of
  { 1.0f, 1.0f, 1.0f }. This replaces the previous flag-based control that
  allowed either uniform or "perceptual" weights with the fixed values
  { 0.2126f, 0.7152f, 0.0722f }. If non-NULL, the metric should point to a
  contiguous array of 3 floats.
*/
void CompressMasked( u8 const* rgba, int mask, void* block, int flags, float* metric = 0 );

// -----------------------------------------------------------------------------

/*! @brief Compresses a 4x4 block of pixels.

  @param rgba     The rgba values of the 16 source pixels.
  @param block    Storage for the compressed DXT block.
  @param flags    Compression flags.
  @param metric   An optional perceptual metric.

  The source pixels should be presented as a contiguous array of 16 rgba
  values, with each component as 1 byte each. In memory this should be:

    { r1, g1, b1, a1, .... , r16, g16, b16, a16 }

  The flags parameter should specify either kDxt1, kDxt3 or kDxt5 compression,
  however, DXT1 will be used by default if none is specified. When using DXT1
  compression, 8 bytes of storage are required for the compressed DXT block.
  DXT3 and DXT5 compression require 16 bytes of storage per block.

  The flags parameter can also specify a preferred colour compressor to use
  when fitting the RGB components of the data. Possible colour compressors
  are: kColourClusterFit (the default), kColourRangeFit (very fast, low
  quality) or kColourIterativeClusterFit (slowest, best quality).

  When using kColourClusterFit or kColourIterativeClusterFit, an additional
  flag can be specified to weight the importance of each pixel by its alpha
  value. For images that are rendered using alpha blending, this can
  significantly increase the perceived quality.

  The metric parameter can be used to weight the relative importance of each
  colour channel, or pass NULL to use the default uniform weight of
  { 1.0f, 1.0f, 1.0f }. This replaces the previous flag-based control that
  allowed either uniform or "perceptual" weights with the fixed values
  { 0.2126f, 0.7152f, 0.0722f }. If non-NULL, the metric should point to a
  contiguous array of 3 floats.

  This method is an inline that calls CompressMasked with a mask of 0xffff,
  provided for compatibility with older versions of squish.
*/
inline void Compress( u8 const* rgba, void* block, int flags, float* metric = 0 )
{
  CompressMasked( rgba, 0xffff, block, flags, metric );
}

// -----------------------------------------------------------------------------

/*! @brief Decompresses a 4x4 block of pixels.

  @param rgba     Storage for the 16 decompressed pixels.
  @param block    The compressed DXT block.
  @param flags    Compression flags.

  The decompressed pixels will be written as a contiguous array of 16 rgba
  values, with each component as 1 byte each. In memory this is:

    { r1, g1, b1, a1, .... , r16, g16, b16, a16 }

  The flags parameter should specify either kDxt1, kDxt3 or kDxt5 compression,
  however, DXT1 will be used by default if none is specified. All other flags
  are ignored.
*/
void Decompress( u8* rgba, void const* block, int flags );

// -----------------------------------------------------------------------------

/*! @brief Computes the amount of compressed storage required.

  @param width    The width of the image.
  @param height   The height of the image.
  @param flags    Compression flags.

  The flags parameter should specify either kDxt1, kDxt3 or kDxt5 compression,
  however, DXT1 will be used by default if none is specified. All other flags
  are ignored.

  Most DXT images will be a multiple of 4 in each dimension, but this
  function supports arbitrary size images by allowing the outer blocks to
  be only partially used.
*/
int GetStorageRequirements( int width, int height, int flags );

// -----------------------------------------------------------------------------

/*! @brief Compresses an image in memory.

  @param rgba     The pixels of the source.
  @param width    The width of the source image.
  @param height   The height of the source image.
  @param blocks   Storage for the compressed output.
  @param flags    Compression flags.
  @param metric   An optional perceptual metric.

  The source pixels should be presented as a contiguous array of width*height
  rgba values, with each component as 1 byte each. In memory this should be:

    { r1, g1, b1, a1, .... , rn, gn, bn, an } for n = width*height

  The flags parameter should specify either kDxt1, kDxt3 or kDxt5 compression,
  however, DXT1 will be used by default if none is specified. When using DXT1
  compression, 8 bytes of storage are required for each compressed DXT block.
  DXT3 and DXT5 compression require 16 bytes of storage per block.

  The flags parameter can also specify a preferred colour compressor to use
  when fitting the RGB components of the data. Possible colour compressors
  are: kColourClusterFit (the default), kColourRangeFit (very fast, low
  quality) or kColourIterativeClusterFit (slowest, best quality).

  When using kColourClusterFit or kColourIterativeClusterFit, an additional
  flag can be specified to weight the importance of each pixel by its alpha
  value. For images that are rendered using alpha blending, this can
  significantly increase the perceived quality.

  The metric parameter can be used to weight the relative importance of each
  colour channel, or pass NULL to use the default uniform weight of
  { 1.0f, 1.0f, 1.0f }. This replaces the previous flag-based control that
  allowed either uniform or "perceptual" weights with the fixed values
  { 0.2126f, 0.7152f, 0.0722f }. If non-NULL, the metric should point to a
  contiguous array of 3 floats.

  Internally this function calls squish::CompressMasked for each block, which
  allows for pixels outside the image to take arbitrary values. The function
  squish::GetStorageRequirements can be called to compute the amount of memory
  to allocate for the compressed output.
*/
void CompressImage( u8 const* rgba, int width, int height, void* blocks, int flags, float* metric = 0 );

// -----------------------------------------------------------------------------

/*! @brief Decompresses an image in memory.

  @param rgba     Storage for the decompressed pixels.
  @param width    The width of the source image.
  @param height   The height of the source image.
  @param blocks   The compressed DXT blocks.
  @param flags    Compression flags.

  The decompressed pixels will be written as a contiguous array of width*height
  16 rgba values, with each component as 1 byte each. In memory this is:

    { r1, g1, b1, a1, .... , rn, gn, bn, an } for n = width*height

  The flags parameter should specify either kDxt1, kDxt3 or kDxt5 compression,
  however, DXT1 will be used by default if none is specified. All other flags
  are ignored.

  Internally this function calls squish::Decompress for each block.
*/
void DecompressImage( u8* rgba, int width, int height, void const* blocks, int flags );

// -----------------------------------------------------------------------------

} // namespace squish

#endif // ndef SQUISH_H

